Check out some of the clubs around:
Puget Sound Trialers
Columbia Observed Trials Assn.
NATC trials clubs
There don't appear to be any clubs in your area but the trials that they put on will probably be around the state and perhaps closer to where you are.
Try showing up to one of their trials with your EC250. There is generally a beginner/big bike line that can be ridden with an Enduro bike. Also they will often do clinics before trials as well. Just to give yourself an idea.